[Matt Henderson]

All,

Bit of a random one but is air temperature or new water i.e. rain the greatest infleunce on river/loch water temperature?  I noticed when fishing last week that the Dee was like a bath.  I just wondered whether the cooler weather will drop the temperature or whether it will require rain to drop the temperature?

Thanks

Matt

[Rob Brownfield]

Lots of factors to take into consideration with that one.

Still cool air will not cool water as quickly as windy cool air.

Turbulant sections of river will cool quicker than still/slow moving section of river.

Rain can be warm or cool, and can fall on hot roads/warm earth and initially warm up until the soil starts to cool as the water runs off. (Think ground source heating that warms water).

Water running off or predominantly town/city streets will be a different temperature to that running off of mountainsides/fields.

But, I think it is fair to say a sudden, heavy and prolonged downpour would have a greater cooling effect than a cool day.